166 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. III. 



zygomatic width, 19; interorbital constriction, 6; greatest width 

 of brain case, 14; mastoid breadth, 13.5; length of nasals, n; 

 width of rostrum, 6; palatal length to anterior edge of tooth'row 

 from palatal arch, 5; length of mandible, angle to alveolus of 

 incisor, 19; height at condyle, 7; at coronoid process, n; length 

 of upper tooth row at alveolar border, 7. 



This gopher, while its nearest relative would seem to be T. 

 douglasi, is yet apparently distinct from all the forms that have 

 received a name up to this time. Its geographical position is 

 peculiar, and of this Mr. Heller in his notes writes as follows: 

 " It is isolated from T. douglasi. On the south its range prob- 

 ably connects with the Crescent City form (7! laticeps), which is 

 very different; on the east it may connect with T. leucodon, and 

 on the north the genus is apparently lacking until the Umpqua 

 is reached." It therefore stands alone, surrounded by very differ- 

 ent forms from which it is easily distinguished. I have much 

 pleasure in bestowing Mr. Heller's name upon this and the fol- 

 lowing species, in recognition of his most capable services to this 

 Institution, for which he is an official collector. 



FAM. HETEROMYID.E. 



SUBFAM. HETEROMYIN.E. 



GENUS PEROGNATHUS. 



A. CHJETODIPUS. 



Perognathus helleri. Sp. nov. 



Type locality. San Quentin, Lower California, Mexico. 



Geogr. distr. Type locality only. 



Gen. char. Size similar to P. p. arenarius ; color entirely 

 different, lateral line conspicuous. Skull with shorter nasals, 

 broader rostrum, wider interorbital space, brain case broader, 

 mastoids less prominent, and bullae smaller and more pointed 

 anteriorly. 



Color. Above mixed black and dark buff, giving a dark yel- 

 lowish brown appearance to the upper parts, very different froi 

 the pale buffy drab oiP. p. arenarius. Distinct bright buff later* 

 line from nose to rump; under parts pure white; tail above darl* 

 brown, almost dusky; beneath pure white, pencil like upper pai 

 dusky; hands and feet gray, ears dark brown. 



